Cleanliness verification and defining acceptable cleanliness levels

The key to surface finishing is a 'properly' prepared surface. Defining and maintaining the surface preparation at 'proper' levels is, at best, subjec tive. Often the failure of surface preparation processes is not discovered until problems, such as poor adhesion, occur downstream resulting in non-co nformance owing to poor quality surface cleanliness. To assure consistent q uality of surface cleanliness, it is important to define how clean the surf ace has to be. This paper discusses the types of contamination, the most co mmon surface cleanliness measuring/verification techniques, factors affecti ng the choice of cleanliness measuring/verification techniques, and a struc tured approach to defining the 'acceptable level of cleanliness'. In short, this paper discusses the ways to define how 'clean' is clean.